Could American expats swing the U.S. presidential election?

An international civic organization has launched a campaign to encourage American expatriates to vote in November’s presidential election and defeat Donald Trump.

Avaaz, an organization that promotes citizen activism on a range of causes, estimates there are 1 million U.S. citizens living in Mexico and believes that many would not vote for the Republican Party candidate.

Estimates of exactly how many American citizens live overseas vary widely, but most fall somewhere between 3 million and 9 million. The number who are also eligible to vote in U.S. elections is even harder to pin down.

Americans living abroad are a “more worldly group of people, who understand that the United States is part of a global community and want to be a good citizen of that global community,” said Avaaz deputy director Emma Ruby-Sachs.

Many are from swing states, she said, meaning their vote could have a big impact.

To help encourage those citizens to vote, the organization launched an online tool on Wednesday Sept. 21 that is intended to simplify the voter registration process and issue a reminder to voters to cast their absentee ballots before the deadline.

Ruby-Sachs said the official process is not user-friendly so Avaaz designed a system that asks a series of questions whose answers generate a completed registration form.

Because many states require registration prior to a deadline in October, Avaaz is calling its initiative “the October surprise that will defeat Trump.”

The organization is planning an event Sunday at Ángel de la Independencia in Mexico City where American citizens are invited to bring a scanned copy of their passport and complete their voter registration.

Avaaz wants all American expats to register from abroad, and reminds them to cast their absentee ballots before the stated deadline. The progressive group hopes that encouraging the American diaspora to vote will help accomplish its decidedly partisan goal: “Defeat Donald Trump.”

“For the whole world, whether we like it or not, the United States is a global superpower, which means it can lead us to a brighter future … or it can undo progress,” said Ruby-Sachs. “People who either live in the United States or are American citizens have a role to play in that and have a responsibility to play that role fully.”

Ruby-Sachs said Avaaz members decided to launch the voter registration initiative because of Trump’s “seeming lack of regard for some of the value norms we all subscribe to.” She specifically cited statements Trump has made indicating he would be willing to use nuclear weapons.

Of course, in U.S. politics the popular vote is largely symbolic. Who is ultimately named the victor in November will depend on which candidate secures an absolute majority of at least 270 votes from the Electoral College.

But Ruby-Sachs said many Americans living abroad hail from swing states, particularly Florida, where just a few hundred or thousand ballots can determine the winner. In 2012, most ballots sent to overseas voters came from election boards in Texas, California, Florida and Washington state, according to the Election Assistance Commission.